Crush Golden Grahams in a food processor or place them in a bag and smash with a rolling pin just until the pieces are broken up into smaller pieces. Do not over-process. Pour into a medium bowl and set aside.
In a large bowl, add the molasses and instant coffee to the melted butter and stir until the coffee is dissolved. Mix in the cocoa powder. In a separate bowl, whisk together the flour, baking soda, and salt.
Add the sugar, eggs, and yolk to the butter mixture and stir. Add the dry ingredients to the wet ingredients and mix until combined. Fold in the marshmallows.
Using a large cookie scoop or ice cream scoop, portion the dough into balls and roll each ball in the crushed Golden Grahams. Place onto a sheet pan with parchment paper and allow to rest for 2-3 hours in the freezer or refrigerator.
Bake the cookies at 345℉ for 10-12 minutes until puffed and the center is set. Allow cookies to cool on the pan until firm enough to move to a wire rack and cool completely.